1. Field of the Invention
The present invention relates to a machine vision system, such as those used to inspect objects moving along a manufacturing assembly line; and more particularly to configuring software for the machine vision system to execute on a particular computer.
2. Description of the Related Art
Machine vision systems include a camera for producing a video image of an object to be analyzed and a computer that receives the video image and executes software that analyzes the image. The computer may also be programmed to operate other equipment in response to the results of the analysis. For example, if the image analysis determines that a product on a manufacturing assembly line has a defect, the computer may operate an actuator that diverts the defective product off the assembly line.
The user of a machine vision system is able to purchase the camera and a circuit board that inserts into a conventional personal computer to interface the camera to that computer. The circuit board stores a snapshot video image for analysis by software that is executed on the personal computer. Such software available from a number of companies, such as the VisionPro® software marketed by Cognex Corporation of Natick, Massachusetts, USA. The image processing software includes a basic program and a library of a large number routines, known as tools or tool routines, which enable the basic program to perform specific operations. For example, different tool routines are provided to perform pattern matching, barcode reading, color identification, finding edges of objects, and locating lines and geometrical shapes, as well as other functions.
The user configures the software to analyze images of a particular object, such as a product traveling along an assembly line for example. In doing so, the user selects the specific tool routines needed to perform the desired image analysis to adapt the basic program for that application. For example, the software may be configured to determine whether a pattern in an acquired image of the object matches a reference pattern stored in the computer memory. Such pattern matching can be employed to determine whether a product has been properly manufactured with various elements, such as holes and components, present and properly located.
Historically the machine vision software ran on a computer that had a single processor. In recent years, inexpensive multiple processor computers have become available. For example, personal computers are now available with multiple “core” processors from Intel Corporation of Santa Clara, Calif., USA, which have two or four separate cores in the single integrated circuit. Often these devices are referred to as a dual or quad core processor in that the cores are formed on a single integrated circuit, but in essence, the cores are separate processors which execute different sets of instructions simultaneously and independently. Another version of a multiple processor computer can be produced with totally separate integrated circuits forming each individual processor. In addition computers have a general purpose processor and a special purpose processor, such as a math or geometry coprocessor, for executing specific types of instructions. Thus the term “multiple processors” refers to any computer that has components that enable different sets of program instructions to be executed simultaneously or in parallel. Such different sets of program instructions may be from different software program or from the same software program. Execution of different sets of program instructions simultaneously in parallel on multiple processors is distinguished from “concurrent execution” of different sets of program instructions which occurs in a time division multiplexed manner on one processor.
The increase in availability of multiple processor computers has lead the developers of machine vision software to adapt that software for execution on those computers. The suite of software tool routines is often provided with two versions of each tool routine, one for a single processor system and another version that can be executed on multiple core processors. This required the end user, when selecting a particular tool routine during the program configuration for a specific application, to choose either the single processor or a multiple core version of that tool routine for incorporation into the application program. Because machine vision application programs frequently contained a relatively large number of tool routines, this tool by tool designation of the number of processors was time consuming. During subsequent execution machine vision application program, the multiple core version of each tool routine automatically used all the processor cores on the processor and could not be configured to use less that all the processor cores.
Nevertheless, there were times when one of the processor cores has to be dedicated to executing another application program and thus less that all the cores of the processor integrated circuit were available for execution of a machine vision program tool routine. If in that situation the machine vision program was configured to use all the processors on the computer, execution of that program had to contend with other programs demanding to use some of the same processors. Therefore previous machine vision software for multiple processor computers was not optimized for a variety of possible computer operating conditions and situations.